A polysilazane, when heated, is converted into silica or a siliceous substance (hereinafter simply referred to as SiO.sub.2 substances).
The SiO.sub.2 substances thus formed have excellent insulating properties and are utilized in the electric and electronic fields as an insulating film.
Known polysilazanes, however, have a drawback because, without being modified, conversion rate thereof to SiO.sub.2 substances is low and because a high calcination temperature is required for the conversion thereof into SiO.sub.2 substances.
To solve the above problems, such a proposal has been made that a polysilazane is reacted with a reactive compound as a modifying agent to form a modified polysilazane.
JP-A-H6-128529 proposes a modified polysilazane obtained by reacting a polysilazane with an alkanolamine represented by the general formula: NH.sub.n (ROH).sub.3-n (where R is an alkyl group and n is an integer of 0-2).
In the case of this modified polysilazane, however, it is necessary that a polysilazane be reacted with an aminoalcohol in the form of a methanol or ethanol solution, because of strong hydrophilicity of the aminoalcohol. On the other hand, methanol and ethanol are highly reactive with polysilazanes and can easily decompose the polysilazanes. Therefore, an addition of a large amount of an alcohol to a polysilazane causes problems that the siliceous substance films obtained by calcination of the polysilazane films have a reduced density.
It is an objective problem of the present invention to provide a method of modifying a polysilazane with an amine residue-containing hydroxyl compound without using a lower alcohol such as methanol or ethanol and an amine residue-containing polysilazane obtained by such a method.